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StocksMediumUpdated×2•Originally published 9 May 2026•Updated 10 May 2026•

1 min read

Lumentum Holdings to Join Nasdaq-100 Index Replacing CoStar Group

Key Facts

1Lumentum Holdings Inc. will join the Nasdaq-100 Index prior to the market open on Monday, May 18, 2026.

2Lumentum will replace CoStar Group, Inc. in the index.

Nasdaq has announced that Lumentum Holdings Inc. (LITE) will join the Nasdaq-100 Index, effective prior to the market open on Monday, May 18, 2026, replacing CoStar Group, Inc. (CSGP). The removal comes as CSGP trades at a high P/E ratio of 546.17x, suggesting a potential overvaluation despite its operational strengths. However, recent insider buying activity within CoStar Group has been noted, reflecting internal confidence in the company's long-term trajectory despite its exit from the benchmark. Analysts expect the inclusion of LITE to drive significant buying pressure from passive index-tracking funds. Investors are now weighing CoStar's high valuation metrics against the positive signal sent by insider transactions. These adjustments are part of Nasdaq's periodic rebalancing to ensure adherence to index methodology standards.

24 days ago

Version History

1 additional source confirmed this story

Version 224 days ago

What changed: Added specific valuation metrics for CoStar Group (P/E ratio) and noted recent insider buying activity.

Version 126 days ago

What changed: Added context regarding Lumentum's strong year-to-date performance ranking within the S&P 500 index.